Work is continuing to determine the renal defects in partially hepatectomized rats. In such animals sodium and water excretion, urine osmolality, tubular water reabsorption, and distal sodium delivery are significantly depressed. Further work will include the relationship of tubular water reabsorption versus increasing osmolal clearance during infusion of hypertonic saline plus vasopressin and the sodium content of tissue from various areas of the kidney.